1. Field of the Invention
The present invention relates to an electromagnetic wave radiation coaxial cable and a communication system using the same.
2. Description of the Related Art
Conventionally, opened coaxial cables and leaky coaxial cables have been proposed as a transmitting antenna for mobile communication. For example, Japanese Patent Laid-Open No. 9-198941 (JP-A 9-198941) and Japanese Patent Laid-Open No. 2010-103685 (JP-A 2010-103685) disclose the conventional opened coaxial cable and the conventional leaky coaxial cable, respectively.
Each of opened coaxial cables as described in FIGS. 10A and 10B of JP-A 9-198941 has a helical (spiral) opened groove. When a high frequency signal (i.e. radio frequency signal) is supplied to the opened coaxial cable, the electromagnetic field is leaked out through the opened groove. A receiving antenna provided outside detects the leaked electromagnetic field by inductive coupling.
On the other hand, a leaky coaxial cable as described in FIG. 7 of JP-A 9-198941 and FIG. 1 of JP-A 2010-103685 has a slot. When a radio frequency signal is supplied to the leaky coaxial cable, the electromagnetic field is radiated through the slot. A receiving antenna provided outside detects the radiated electromagnetic wave.